Computed tomography examination of the face of
Macaca anderssoni (Early Pleistocene, Henan, northern China): implications for the biogeographic history of Asian macaques
Ito T, Nishimura TD,
Ebbestad JOR, Takai M
anderssoni, a fossil macaque from the Early Pleistocene of northern China, has attracted much
attention from researchers in terms of reconstructing the biogeographic history of Asian macaques, while
its phylogenetic position remains debatable. In the present study, we evaluated patterns of variation in
external and internal craniofacial morphologies among four phylogenetic groups of extant macaques (the
fascicularis, sinica, silenus, and sylvanus groups), using computed tomography and multivariate analyses.
We also reassessed the holotype of M. anderssoni, a partial cranium preserving the face and palate, to
evaluate the phylogenetic group to which M. anderssoni is most closely related. Facial elongation was
found to be significantly influenced by size. The particular combination of some allometric and nonallometric
shape components was found to reflect phylogenetic relationships; however, these features
of M. anderssoni fall intermediate among the four phylogenetic groups, with no typical similarities to any
one group. The variations in nasal cavity shape were found to reflect phylogenetic relationships but those
of the maxillary sinus did not. Macaca anderssoni has a nasal cavity that is laterally expanded anteriorly
and constricted posteriorly, a unique morphology among macaques and shared only with larger members
of the sinica group. This unique feature is considered to be a derived condition among macaques,
suggesting that M. anderssoni is phylogenetically related to the sinica group (especially
M. thibetana, and M. arctoides) and that the populations of the sinica group were distributed in northern
China during the Early Pleistocene. Currently, the populations of the sinica group are not distributed in
northern East Asia, while those of the fascicularis group are. Thus, probably due to climatic deterioration
in the Late Pleistocene, the former lineage has retreated southward or has become extinct in this region,
being replaced by the latter lineage.
Journal of Human Evolution 72: 64-80JUN/27/2014
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